As is well known, cages for rolling bodies have the purpose of securely guiding the rolling bodies between the rolling body races and to keep the rolling bodies at a distance from each other. It is only in this manner that a uniform load distribution is facilitated, a mutual interference of the rolling bodies is prevented and, thus, a proper function of the roller bearing is ensured. In addition, the expert desires to accommodate as many rolling bodies as possible in the roller bearing in a compact manner, so that roller bearings for the highest demands can be made available through a high density of the rolling bodies. However, this makes it necessary to provide the corresponding numbers of pockets or free spaces in the roller bearing cage and, in turn, leads to a structural weakening of the cage. This results in an insufficient stiffness and an increased danger of a mechanical failure of the cage during operation.
In the field of needle thrust bearings, bearings which are W-shaped or Sigma-shaped in cross-section have been found useful in this connection. As a rule, these cages are constructed as a single piece and have a relatively high stiffness with a higher achievable roller body density.
A cage for rolling bodies of this type is known from DE 1 840 219 U. In that case, the cage is constructed for cylindrical rolling bodies and has webs with a specially configured profile, such that the web sections extending parallel to the horizontal divisional plane of the rolling bodies have a greater width than the web sections extending transversely thereto, and the guidance of the rolling bodies is therefore exclusively carried out by the web sections which extend parallel to the divisional plane of the rolling bodies. The profile of the webs is suitable for limiting the freedom of mobility of the rolling bodies in two degrees of freedom (to even almost fix the rolling bodies in these degrees of freedom), namely in the circumferential direction as well as in the axial direction of the cage.
In the case of a mechanical failure of the cage (rupture of one of the side walls), which is usually caused by external influences, an “overrolling” by the rolling bodies in the area of the damaged cage may occur, i.e., the rolling bodies leave their race or functional diameter in the radial direction. This leads to a local weakening of the load bearing capacity of the bearing and may possibly cause further damage.
A cage made of synthetic material in a single piece for ball-shaped rolling bodies is described in DE 10 2006 015 547 A1, wherein projections protruding axially towards the cage produce cell-like chambers for the individual rolling bodies and, thus, it is ensured that the rolling bodies are spaced apart from each other in the circumferential direction. An assembly of rolling bodies at the cage takes place partially by widening in the manner of clips directly spaced-apart projections which are shaped especially for this purpose. The diameter of the cell-like chambers is dimensioned in such a way that a significant play is made possible for the rolling bodies in order to be able to change their position relative to the chambers in the radial and in the circumferential directions.